/*
 *  linux/kernel/serial.c
 *
 *  (C) 1991  Linus Torvalds
 */

/*
 *    serial.c
 *
 * This module implements the rs232 io functions
 *    void rs_write(struct tty_struct * queue);
 *    void rs_init(void);
 * and all interrupts pertaining to serial IO.
 */

#include <linux/tty.h>
#include <linux/sched.h>
#include <asm/system.h>
#include <asm/io.h>

#define WAKEUP_CHARS (TTY_BUF_SIZE/4)

extern void rs1_interrupt(void);
extern void rs2_interrupt(void);

static void init(int port)
{
    outb_p(0x80,port+3);    /* set DLAB of line control reg */
    outb_p(0x30,port);    /* LS of divisor (48 -> 2400 bps */
    outb_p(0x00,port+1);    /* MS of divisor */
    outb_p(0x03,port+3);    /* reset DLAB */
    outb_p(0x0b,port+4);    /* set DTR,RTS, OUT_2 */
    outb_p(0x0d,port+1);    /* enable all intrs but writes */
    (void)inb(port);    /* read data port to reset things (?) */
}

void rs_init(void) {
    set_intr_gate(0x24,rs1_interrupt);  // set up serial port 1 interruption
    set_intr_gate(0x23,rs2_interrupt);  // serial port 2 interruption
    init(tty_table[1].read_q.data);     // initialize serial port 1
    init(tty_table[2].read_q.data);     // initialize serial port 2
    outb(inb_p(0x21)&0xE7,0x21);        // Allow IRQ3 and IRQ4
}

/*
 * This routine gets called when tty_write has put something into
 * the write_queue. It must check wheter the queue is empty, and
 * set the interrupt register accordingly
 *
 *    void _rs_write(struct tty_struct * tty);
 */
void rs_write(struct tty_struct * tty)
{
    cli();
    if (!EMPTY(tty->write_q))
        outb(inb_p(tty->write_q.data+1)|0x02,tty->write_q.data+1);
    sti();
}
